【正文】 ate = MCLK/(UART_DIV_CNT0+1)/16167 。if UART_DIV_CNT1==xxx1 baud rate = MCLK/(UART_DIV_CNT0+1)/16/16 153 ldr r0, =URXBUF0154 ldr r1, [r0] 。*************************************************137 UART_DIV_CNT0 EQU 26138 UART_DIV_CNT1 EQU 0139140 InitUart141 ldr r0, =ULCON0142 ldr r1, =DATA8b :OR: STOPb1 :OR PARITY_NO143 str r1, [r0]144145 ldr r0, =UCON0146 ldr r1, =RX_STAT_INT|9147 str r1, [r0]148 149 ldr r0, =UBRDIV0150 ldr r1, =UART_DIV_CNT04|UART_DIV_CNT1151 str r1, [r0] 。*************************************************129 InitTimer130 ldr r0, =TMOD131 ldr r1, =0132 str r1, [r0] 。disable XIRQ 03, dma req,ack, timer 0,1 output122123 ldr r0, =IOPDATA124 ldr r1, [r0] 。*************************************************114 InitPort115 ldr r0, =IOPMOD116 ldr r1, =1117 str r1, [r0] 。*************************************************106 InitInterrupt107 ldr r0, =INTMSK108 ldr r1, =0x3fffff109 str r1, [r0] 。00000000103 DCD amp。00000000101 DCD amp。0000006099 DCD amp。0000006097 DCD amp。0000006095 DCD amp。ce2983fd 8081 EXPORT ResetMemSet82 ResetMemSet83 adr r0, ResetMemPara84 ldmia r0, {r1r11}85 ldr r0, =ROMCON086 stmia r0, {r1r11}87 nop88 nop8990 mov pc, r14 9192 ResetMemPara93 DCD amp。1004039878 DCD amp。1000039876 DCD amp。1084206074 DCD amp。1084206072 DCD amp。1204006070 DCD amp。ce2983fd 5354 EXPORT RemapMemory55 RemapMemory56 adr r0, RemapMemPara57 ldmia r0, {r1r11}58 ldr r0, =ROMCON059 stmia r0, {r1r11}60 nop61 nop62 ldr r0, =IRQ_SVC_VECTOR63 ldr r1, =IRQ_SERVICE 。1004039851 DCD amp。1000039849 DCD amp。398 。1084206047 DCD amp。1084206045 DCD amp。1084006043 DCD amp。60 。0x3f800001213 。200 78 AREA text, CODE, READONLY 910 SFR_BASE EQU 0x3ff 。205 RamBaseAddr EQU amp。 a1 = r0194 mov r2, TIP_SIZE195 0 196 ldr r3, [r1], 4197 str r3, [r0], 4198 subs r2, r2, 1199 bne %B0200 201 sub r0, r0, TIP_SIZE*4202 mov pc, r0 行184202定義了從FLASH固定地址BIOS_LOAD＝0x1000啟動(dòng)程序的函數(shù)，似乎是重新啟動(dòng)的程序。 End of variable RAM space176 177 BaseOfROM DCD |Image$$RO$$Base|178 TopOfROM DCD |Image$$RO$$Limit|179 BaseOfBSS DCD |Image$$RW$$Base|180 BaseOfZero DCD |Image$$ZI$$Base|181 EndOfBSS DCD |Image$$ZI$$Limit|. 定義從FLASH啟動(dòng)程序的函數(shù)184 TIP_SIZE EQU 256185 186 IMPORT ResetMemSet187 EXPORT trans_to_boot188 trans_to_boot189 mov lr, r1 。 Preinitialised variables174 IMPORT |Image$$ZI$$Base| 。 ROM code start 172 IMPORT |Image$$RO$$Limit| 。170 。行165將返回地址進(jìn)行設(shè)置。行142148將內(nèi)存中的ZI段初始化為0。行119128將bootloader的RO段拷貝入內(nèi)存。InitSystem函數(shù)的作用是進(jìn)行內(nèi)存、堆棧、LED端口、串口、定時(shí)器以及中斷的初始化工作，（）。SYS_RST_HANDLER異常處理程序與其它異常處理程序有很大不同，行110113使得處理器進(jìn)入SVC模式，并且禁止FIQ與IRQ。enter svc mode and disable irq,fiq111 bic r0, r0, ModeMask112 orr r0, r0, (SVC32Mode :OR: IRQ_BIT :OR: FIQ_BIT)113 msr cpsr_c, r0114 115 IMPORT InitSystem116 bl InitSystem 117 118 adr r0, ResetEntry119 mov r3, (RamBaseAddr16)120 ldr r1, BaseOfROM 121 ldr r2, TopOfROM 122 add r1, r1, r3123 add r2, r2, r3124 0 125 ldmia r0!, {r4r11}126 stmia r1!, {r4r11}127 cmp r1, r2128 bcc %B0129 130 sub r1, r1, r2131 sub r0, r0, r1 132 ldr r1, BaseOfBSS133 ldr r2, BaseOfZero134 add r1, r1, r3 135 add r2, r2, r3 136 1 137 cmp r1, r2 138 ldrcc r4, [r0], 4139 strcc r4, [r1], 4 140 bcc %B1141 142 mov r0, 0143 ldr r2, EndOfBSS144 add r2, r2, r3145 3 146 cmp r1, r2147 strcc r0, [r1], 4148 bcc %B3 149 150 IMPORT RemapMemory 151 152 adr r0, ResetEntry153 ldr r1, =RemapMemory 154 ldr r2, BaseOfROM155 sub r2, r1, r2156 add r0, r0, r2157 add r1, r2, r3158 mov r2, 32159 0 160 ldr r3, [r0], 4161 str r3, [r1], 4162 subs r2, r2, 1163 bne %B0164 165 ldr lr, GotoMain 166 b RemapMemory 行67166定義了7種模式異常的處理函數(shù)具體地：UDF_INS_HANDLER 執(zhí)行UDF_INS_VECTOR內(nèi)存所保存的指令后，返回到異常發(fā)生之前的狀態(tài)。. 異常處理程序定義67 UDF_INS_HANDLER68 stmfd sp!, {r0r3, lr}69 ldr r0, =UDF_INS_VECTOR70 mov lr, pc71 ldr pc, [r0]72 ldmfd sp!, {r0r3, pc}^73 SWI_SVC_HANDLER74 stmfd sp!, {r0r3, lr}75 ldr r0, =SWI_SVC_VECTOR76 mov lr, pc77 ldr pc, [r0]78 ldmfd sp!, {r0r3, pc}^79 INS_ABT_HANDLER80 sub lr, lr, 481 stmfd sp!, {r0r3, lr}82 ldr r0, =INS_ABT_VECTOR83 mov lr, pc84 ldr pc, [r0]85 ldmfd sp!, {r0r3, pc}^86 DAT_ABT_HANDLER87 sub lr, lr, 488 stmfd sp!, {r0r3, lr}89 ldr r0, =DAT_ABT_VECTOR90 mov lr, pc91 ldr pc, [r0]92 ldmfd sp!, {r0r3, pc}^93 IRQ_SVC_HANDLER94 sub lr, lr, 495 stmfd sp!, {r0r12, lr} 96 mrs r0, spsr97 stmfd sp!, {r0}98 ldr r0, =IRQ_SVC_VECTOR99 ldr pc, [r0] 100 FIQ_SVC_HANDLER101 sub lr, lr, 4102 stmfd sp!, {r0r12, lr} 103 mrs r0, spsr104 stmfd sp!, {r0}105 ldr r0, =IRQ_SVC_VECTOR106 ldr pc, [r0]107 108 。. 定義系統(tǒng)異常向量表46 ResetEntry47 b SYS_RST_HANDLER48 b UD